Turning now to the 4th of the july in this country. A huge swath of the nation is gripped by a record heat wave. Much of the southwest is sweating through triple digits and the east is facing another day of torrential rains and flash floods. We're in maricopa county with the very lest. Reporter: Summer's heat -- already a weather blockbuster. Today it's 110 degrees in phoenix. Records this week melted away. Yuma, arizona -- 118. Las vegas -- 117. Death valley hit 129 -- five degrees shy of the hottest temperature ever recorded on earth. The problem is -- as people warm the climate -- heat waves are getting hotter. The danger is -- it's not cooling off at night. You know the sun goes down. You expect temperatures to fall off, but they don't and your body just does not get a break at all. Reporter: Every year, extreme heat kills more people than tornadoes, hurricanes, floods and lightning combined. Forecasters blame a "kink" in the jet stream for causing this week's wild swings -- including pounding rain and flash floods across the southeast. Some locations have seen upwards of one foot of rain. Within the last couple of days. Reporter: The heat is also revving up a wildfire season that's destroyed more than eight hundred homes -- torched 1.7 million acres -- and claimed the lives of 19 firefighters in prescott, arizona. Today in prescott -- fourth of july celebrations went on as planned. It's a time to celebrate and remember those guys and, you know, know what they did for us. Reporter: The weather today offered some relief from the heat in a town that deserves a break.

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